Full legalisation of retail marijuana came into effect in January, but decision to jump ahead of US national drug policy is exacerbating legal tensions which may have profound consequences for whether this unique experiment spreads

Before taking into account the construction boom, the local pot industry is thought to have created 15,000 new jobs over the last four years. Photo: National forest service

A short drive from the “green rush” of Denver's legal marijuana boom, national forest police have been staking out a suspected cannabis plantation, hidden deep in the woods, that is anything but legitimate.

Using aerial reconnaissance and tracking devices attached to resupply trucks, federal special agents were trying to locate the latest gang of armed drug traffickers responsible for more than 100,000 plants discovered growing in national forests since Colorado first began its limited commercial decriminalisation experiment five years ago.

The full legalisation of retail marijuana suppliers and growers, which came into effect in January, might have been expected to mark the end of the matter as far as Colorado's law enforcement authorities were concerned.

Forest police monitoring the sophisticated farms camped out in the vast Rocky mountain wilderness believe most of their production is destined for other US cities such as Chicago, where it is still illegal, rather than local shops.

But the persistence of unregulated grow sites on federal land is just one of many legal tensions exacerbated by the decision of states like Colorado and Washington to jump so far ahead of US national drug policy.

In another example, Colorado legislators this month had to pass a new state law to allow for a cannabis co-operative credit union that would let marijuana businesses open bank accounts and escape the murky world of cash-only transactions.

Yet most national banks and credit card companies remain barred from dealing with the industry and only last month the federal Drug Enforcement Agency raided four marijuana stores in Denver, smashing doors and forcing open safes in the latest crackdown on businesses suspected of money laundering.

The state's next legal amendment is likely to establish Opec-style production caps to deter its legitimate growers from diverting excess supply to illegal dealers in neighbouring states.

But special agents working for the national forest service are already monitoring a second industrial-size grow site in the Colorado mountains that they believe is back up and running after the winter snow without any regard for the strict electronic tagging system required for each plant in regulated facilities.

The contrast between these two worlds – one legal and flourishing, the other illegal and stubbornly disregarding of state lines – can seem baffling, yet it may have profound consequences for whether this unique experiment spreads.

Moving into a 'post-prohibition world'

Down in Colorado's Front Range, the cluster of towns and cities that cling to the eastern edge of the Rockies, the scent of what has been dubbed a commercial “green rush” is hanging in the air – literally. On the road in from Denver airport, several of the state's estimated 800-900 legal growers have taken advantage of cheap warehouse space to open sophisticated indoor facilities, whose odour is clearly discernible by passing motorists.

A worker for the National Forest service team removing one of over 7,000 plants found at St Vrains Creek near Lyons, Colorado. Photograph: National forest service

Even before taking into account the construction boom, the local pot industry is thought to have created 15,000 new jobs over the last four years, with annual sales growing from $400m in 2013 to an estimated $600m this year, according to Vicente.

The scale of the industry, with its heavy regulation and large cash turnover, has created lucrative work for ancillary advisers such as accountants and lawyers. Brian Vicente was co-director of the campaign to legalise recreational marijuana in Colorado, and now reaping the benefits of his advocacy. His law firm is one of the fastest-growing in the state, and with 20 attorneys to service several hundred clients in the industry.

In Vicente Sederberg's wood-panneled offices in downtown Denver, its founding partner acknowledges there are plenty more legal and regulatory obstacles to iron out. “It's a process,” says Vicente. "Marijuana was illegal, by and large, for 80 years. Now we are moving into this post-prohibition world, we are really interested in establishing the most responsible policies possible."

But making sure the industry stays on the right side of the rapidly changing law is vital to its plans for growth in five other states that campaigners hope may join Colorado and Washington in legalising recreational marijuana by the end of 2016.

These include Alaska and Oregon, which are top priorities for campaigners, followed potentially by Massachusetts, Nevada, Arizona and California – a target list which recently prompted Vicente Sederberg to open an office in Boston.

This is going to be a very large national market in five to eight years and banks will absolutely want to work with this industry; it's going to be large and powerful,” adds the law firm's founder.

Vicente has also met elected officials from the UK, Australia, Jamaica and Uruguay, which flew Colorado experts down to South America to advise on how to bring an end to its war on soft drugs.

Visiting one of Denver's scores of new pot shops is indeed a bewildering experience, even for the sober.

Livegreen Cannabis, in the suburb of Edgewater, is typical of many that converted from medical marijuana dispensaries – requiring a doctor's certificate – to a full retail outlet when the law changed in January.

As a saleswoman explains the products and prices on offer, the complexity of the system becomes apparent. There are different supply limits for in-state and out-of-state customers; different tax rates for medicinal and recreational customers and a host of different strains, tinctures and medibles (“edibles that are medicinal”) that compete with a new concentrated form of marijuana called wax

The wide eyes and raspy voices on both sides of the counter suggest locals have less difficulty working out where to start, but visitors looking to consume rather than gawp also have to grapple with a ban on smoking in public places, cars and hotels which has so far mostly prevented the opening of Amsterdam-style coffee shops.

But a short drive away from the city, in the mountains that also host some of America's swankiest ski resorts, there is still a reminder of the industry's grubbier days growing weed in the woods.

The grow site at St Vrains Creek near Lyons, Colorado, where 3,559 and 3,995 plants were confiscated in two separate raids. Photograph: National forest service

With just 35 uniformed patrol officers and six plain clothes special agents to cover 22m acres over five states, the National Forest Service is struggling to cope with an outbreak that leaves a trail of environmental as well as law enforcement headaches.

“Everyone's speculation was, you legalise it and the problem will go away, but we have not seen a decrease,” says Laura Mark, the special agent in charge of the Rocky Mountain region. “And at this point I would say I do not anticipate an impact or reduction in these grows just because marijuana has been legalised.”

The White River national park, where a father and son last stumbled across 3,375 plants while hiking late last September, is not as peaceful as it looks.

White River National Park is home to some illegal growing sites.

Only this month, roads in the area were closed off after a state trooper was shot while pulling over a suspect vehicle.

Ski towns in the area, including world famous resorts like Vail and Aspen, have tried to minimise marijuana suppliers to control any influx of stoned tourists.

But even gnarled park service veterans are impressed at the logistical feats required to maintain plantations as large as 8,700 plants miles from the nearest road.

“These operations are very organised,” says Mark. If we could pull off to the same magnitude the logistical feats that these individuals do in building a city within the forest, it would be pretty amazing.”

This was the campsite used by workers growing 1,600 plants at Indian Creek in the Pike National forest, near Denver, last October. Photograph: National forest service

Pits are dug to create water reservoirs which are then connected to irrigation systems that would put a golf course to shame.

Terraced bunk beds are built in the trees to provide round-the-clock accommodation for crews of farmers and heavily-armed guards, many of whom have come from as far as the drug cartels of Michoacán, Mexico.

Just finding the clearing can be hard enough. Trees felled to make way for the bushes have their stumps painted green to prevent them being spotted from the air. Most are found by accident by hikers or if the wind is in the right direction.

“Once you get out there you are like a mountain goat, crawling up and down hills, hauling plants,” says Mark, a veteran of many raids in Colorado and California. “Elevation, heat, bugs, snakes: it's arduous to say the least.”

'I think the black market is already on its way out'

Less admired are the powerful, but often banned, pesticides and fertilisers left behind by growers which contribute to hundreds of thousands of dollars in clean-up costs for each site.

The park service says that, since the legalisation of regulated marijuana growers in Colorado, it has experienced a drop in support from local law-enforcement agencies, according to the park service. “In a lot of cases they have made a determination that this is a federal issue not a state issue any more and they have stepped back,” says assistant special agent Heiko Bornhoff. “ [They tell us] 'you guys do what you need to do but we are not going to support you in the way we used to',” he adds.

Despite an overall reduction in crime since Colorado's legalisation of marijuana, many law enforcement agents like Bornhoff remain sceptical of the state's ability to enforce regulation prohibiting illegally grown drugs entering the legal distribution chain.

But for the industry's advocates, such attitudes are redolent of the failure of some in the law enforcement community to let go of a pursuit which used to keep many gainfully employed.

Brian Vicente was co-director of the campaign to legalise recreational marijuana in Colorado.

“Since we legalised marijuana – something no one thought we were going to do – we have seen some complaints from law enforcement, which has always been the main obstacle to ending the war on drugs,” says Vicente.

“Police in Colorado used to arrest 10,000-plus people for marijuana possession every single year. They don't do that any more, so those police resources can be marshalled for things that matter: real crime or finding these guys in the forests who are growing marijuana illegally.”

Vicente, the industry's de facto spokesman, acknowledges there is risk that some of the drugs on sale in shops comes from illegal sites like those found in the White River national forest, as legitimate suppliers struggled to keep up with demand.

But he points to the fall in medicinal marijuana prices to near that of illegal street dealers as a sign that momentum has swung decisively away from the cartels and traffickers and in favour of a legitimate industry that will only grow over time.

“I think the black market is already on its way out,” says Vicente. “This is all a process and until our country legalises marijuana there is always going to be some incentive for people to bring marijuana from Colorado to, say, Nebraska. There were bootleggers after prohibition ended, for a little while, but not for long.”

Dispensaries selling cannabis chocolates and bath salts, 'bud-tenders' advising on the best blends, even a marijuana university. As Colorado gears up for full legalisation, Jenny Kleeman gets the dope on Denver's 'green rush'